Clinicopathologic features of active infective endocarditis isolated to the native mitral valve.

Although a number of clinicopathologic studies in patients with active infective endocarditis (IE) have been reported, none have focused on patients studied at necropsy with active IE isolated to the mitral valve. We studied at necropsy 63 patients (aged 12 to 88 years [mean 50], 44 males [70%]) with active IE limited to the native mitral valve: 21 (33%) had preexisting mitral valve disease (rheumatic in 8, prolapse in 3, hypertrophic cardiomyopathy in 1, and mitral annular calcium in 9), and the other 42 patients (67%) had previously normal mitral valves. Of the latter 42 patients, 22 (52%) had recognized predisposing factors to IE: opiate addiction in 14, habitual alcoholism in 6 and/or chronic hemodialysis in 4. Staphylococcus aureus or epidermidis was the responsible organism in 32 patients (51%), and the active IE was associated with an infection elsewhere in the body in 31 patients (50%). The active IE caused rupture of mitral chordae tendineae in 11 patients (18%), perforation of the anterior mitral leaflet in 7 patients (11%), and mitral ring abscess in 10 patients (16%). Grossly visible systemic emboli were found in 44 patients (70%) and 33 (52%) had infarcts in 1 or more body organs. Thus, active IE isolated to the mitral valve in necropsied patients appears to be more common in males than females (2 to 1); the infection more commonly than not involves a preexisting anatomically normal valve rather than a preexisting abnormal one (2 to 1); the vegetations often do not cause or worsen valvular dysfunction; a predisposing factor is commonly present (2 of 3 patients), and the IE commonly is part of a generalized or systemic infection (1 of 2 patients).